Today（今天） is Sunday. The weather is warm and windy. I can wear my shirt（衬衣） and jeans牛仔裤). I fly a kite on the playground. Tom and Jack wear their T-shirt and shorts. They play football. But in Harbin, it's cold. It's snowy. People put on their coat and hats. They can make a snowman(雪人) and skate(滑雪). It’s funny.

It's windy. So I can fly a kite.

下列各组工厂之间，生产协作关系十分密切的是（     ）

人类要解决环境问题，必须树立正确的(　　)

如图，有一个只有短针和长针的时钟，短针OA长6cm，长针OB长8cm，△0AB随着时间的变化不停地改变形状，则△AOB的最大面积为____ cm²．

下列有关导体的说法中正确的是（　　）